Weft stop motion for looms



Dec. 6, 1966 J. L. LLADd 3,289,709

WEFT STOP MOTION FOR LOOMS Filed June 22, 1964 United States Patent 2 Claims. (or. 139-370 In looms, when the weft yarn is pulled through the shed in order that, once the weft yarn has been gripped by, the slay, the cycle of consecutive picks which form the fabric may be restarted, there are dynamic problems which make it impossible for the Weft to be introduced into the shed at high speeds. In cases where the fabrics are of qualities making it essential to use weak weft yarns which have little twist and which are of a weak construction or composed of remanufactured components, there is the disadvantage that the yarn tension and the rate of weaving cannot be very high, otherwise, the weft yarn may break since in most of such fabrics very little tension is required to be applied to the weft yarns. In particular, there are fabrics, such as fabrics for blankets, baizes and so on, with the special feature that the pick must be made with wefts having no rubbing resistance, that is, with loose wefts.

To obviate these disadvantages in weaving, to prevent the fabrics from having an unsatisfactory appearance and to obviate the production of unserviceable articles, it is known to provide means for detecting a break in the weft yarn which operate to stop the loom in order that a repair may be made and production resumed. In most looms the weft stop motions are disposed at the entry or exit of the weft yarn, so that in the case of a breakage, the loom stops only after the total travel of the yarn carrier. To obviate these difficulties, central weft stop motions have been suggested; unfortunately, those used so far cannot operate at high speeds as, for instance, in looms where the Weft must operate with considerable tension and where the weft yarn counts are very fine.

Most of the known weft stop motions require sensing needles controlled by complicated mechanisms. Also, the known sensing devices may, by the effect of their own Weight on the weft yarn, cause the yarn to break. Since the known weft stop motions sense yarn tension, they must be adjusted at each change of article and adjustment is a great nuisance since the Weft stop motion mechanisms are below the fabric.

It is diffucult to tension the weft yarn correctly for the weft stop motion to operate, with a risk of damaging the selvedges according to the kind of Warp yarn used. In cases Where the weft yarn has a reduced twist and must be woven with reduced tension, a loop or curve may occur beyond the operative limit of the weft stop motion needles.

The known Weft stop motions sense the weft yarn while the yarn is moving and tensed, with a consequent risk of breakage, while in places Where it is required to Weave with loose weft yarns, the weft stop motion may operate as if the weft yarns were broken so that the loom stops unnecessarily. Other weft stop motions produce flaws in the fabric in the event of a failure of any weft stop motion mechanism, due to interference of the driving elements with it.

Of course, all these stoppages reduce the economic eificiency of textile production, and the device according to the invention has been devised to obviate these disadvantages. With the device according to the invention, the loom can run at high speeds and any kind of weft yarn, of very low quality and of any strength, can be used; also,

the Weft can be pulled through the shed without the need of any brake, and so there is no need whatever to tension the weft yarn in the manner necessary in other known devices.

Another advantage of the weft stop motion according to this invention is that it operates when the weft yarn is in a completely stationary position in its location, and the weft stop motion is always in contact with the same place, so that the loom is always in operation because, if there were a hypothetical breakage of the weft yarn, the contacts stopping the loom would operate, in contrast to the known weft stop motions which sense the weft yarn at times when the yarn is in movement and tensed.

This invention, which is of use with any kind of loom, also has the advantages of simplicity and ease of fitting and the improved efficiency which it can provide by allowing high-speed operation; in the event of any weft yarn breakage the loom stops immediately, but if the weft yarn is merely loose by nature, there is no unnecessary stoppage of the loom such as occurs with other kinds of weft stop motions. Also, since the weft stop motion according to the invention comprises a contact drop wire attachment which extends through the reed, that is, between the reed teeth, there is no lateral movement of such attachment and it can therefore never strike the reed, and so no loops can be formed even with very fine warp yarns, while the attachment can be changed to suit the thickness of the weft yarn and warp yarn.

The device according to the invention can be placed on whichever side of the warp is convenient. It can be placed at the centre of narrow looms, and more than one device can be used in wide looms, in order that the loom may stop immediately-in the event of any weft yarn breakage anywhere.

The device according to this invention comprises a drop wire attachment of arcuate shape to allow the passage of the picking device, and the drop wire can be very fine, thin enough to pass through the gaps between the teeth of the reed even if such gaps are very small, there being no chance of the drop wire striking the reed; by tilting around a fixed bearing place disposed after the reed secured to a fixed place of the loom, the other free and pointed end of the drop wire attachment is compelled, even if in the reed gaps, always to be introduced between the warp yarns, so that when the slay reed pulls the weft yarn, the yarn strikes the pointed end of the drop wire and makes it pivot and open an electric contact disposed at the pivot place, such contact being connected, for instance, to a remotely controlled switch and being synchronised with an appropriately shaped cam whose rotation and development coincides with the operate movement of the slay in order that, when operated by any drive of the loom, it originates the transmission of current which is formed by the movement of the cam which is circular except for a small zone formed with a recess adapted to receive a roller adapted to operate the remotely controlled switch, so that when the reed forces the weft yarn into engagement with the pointed end of the drop wire, the remotely controlled switch closes the electric contact because ofcoincidence between the roller thereof and the recess in the cam, only the electric contact of the drop wire attachment staying open provided that the presence of weft yarn has compelled such attachment to rise; if not, that is, if a weft yarn has broken, the drop wire attachment does not pivot and so the associated contact stays closed and earth current is transmitted to the remotely controlled switch; also, because of the rotation of the cam, that end of the contact which bears the roller is at this time disposed in the recess in the cam, thus closing the contact of the switch, so that the earth current flows to a loom stop relay.

The invention will now be described in greater detail 3 by way of example with reference to the accompanying drawings, in which:

FIGURE 1 is a diagram showing the operation of the weft stop motion before the weft yarn is caught by the reed, an example also being shown of how the remotely controlled switch operates;

FIGURE 2 is a similar diagram showing the weft stop motion at the time when the weft yarn caught by the reed is about to reach its end position and the drop wire of the weft stop motion is about to start tilting;

FIGURE 3 is a similar diagram showing the Weft stop motion when the weft yarn has reached the fabricforming place and the weft stop motion is finishing its tilting movement, and

FIGURE 4 is a similar diagram showing the weft stop motion in the event of an absence of breakage of Weft yarn, so that the drop wire does not pivot, an example also being shown of the operation of the remotely controlled switch.

Referring to FIGURE 1, a weft yarn 1 has just been introduced into a shed A, and a slay 2 bearing a reed 3 is in a position to start pulling and beat the weft yarn 1 to a finished fabric 4. A drop wire 5 which is pivotally mounted on a stationary pin 5 secured to the loom and extends through the gaps between the teeth of the reed 3 and therefore through a top layer 6 and bottom layer 7 of warp yarns is at this time in a static position and therefore a contact 9 associated with the drop wire 5 is in contact with a fixed contact 8 through which and through a flexible electric conductor 11 earth current flows to a fixed contact there is a break here since a movable contact 12 is not in engagement with the contact 10, having been lifted by an arm 13 carrying a roller 14 which contacts a cam 15, the rotation of which is adapted to the operative movement of the slay.

Referring now to FIGURE 2, the weft yarn 1 has been pulled by the slay 2 with the reed 3 until it meets the free pointed end 16 of the drop wire 5 thus rotating the drop wire 5 so that the contacts 8 and 9 separate from one another. At the same time the contacts 10, 12 of the remotely controlled switch B close because the arm 13 has engaged in a recess 17 in the cam 15. The loom therefore continues to operate normally.

FIGURE 3 shows the final position phase of the weft yarn 1; as in the previous case, the loom circuit is normal since there is no breakage of a weft yarn.

Referring now to FIGURE 4, the weft yarn has broken and so the drop wire 5, which is unable to pivot in the absence of weft yarn, keeps the contacts 8 and 9 in engagement with one another, so that earth current flows through the conductor 11 to the contact 10 which at this particular time is in contact with the contact 12 because of the arm 13 engaging in the recess 17 in the cam 15. The earth current therefore flows through contacts 18, 19 to a loom stop relay (not shown) which stops the loom automatically.

The details and constructional features used to carry the invention into effect can be varied, and the invention can be modified and added to or be embodied by equivalent means without departing from its scope as defined by the appendant claims.

What I claim is:

1. In a loom, in combination with a reciprocating slay carrying a reed, and remotely controlled switch means in an electric circuit controlling the stop mechanism of the loom, which switch means are synchronously operated with the reciprocating movement of the slay, a weft stop motion comprising a stationary support secured to the loom frame at the rear of said reed, thin feeler means carried on said support for pivotal movement and passage of a free end thereof through a dent of the reed, an electric contact comprising contact means at the other end of said feeler means and movable therewith and stationary contact means at the loom electrically connected to said switch means, said electric contact remaining open when said feeler means are pivoted upwardly by a respective weft and being closed when the free end of said feeler means is in dropdown position due to lack of contact with a weft, closure of said electric contact and switch means actuating said stop mechanism of the loom.

2. A weft stop motion for looms as claimed in claim 1, in which the said feeler means is adapted to operate when the weft yarn is in completely static inoperative position.

References Cited by the Examiner UNITED STATES PATENTS 169,596 11/1875 Stillman 139-374 1,975,747 10/1934 Hewton 139370 2,819,737 1/1958 Opletal 139370 2,977,996 4/1961 Ancet et al. 139-370 3,145,739 8/1964 Metzler l39-370 FOREIGN PATENTS 1,140,614 3/1957 France.

396,334 5/ 1924 Germany.

MERVIN STEIN, Primary Examiner.

DONALD W. PARKER, ROBERT R. MACKEY,

Examiners. J. KEE CHI, Assistant Examiner. 

1. IN A LOOM, IN COMBINATION WITH A RECIPROCATING SLAY CARRYING A REED, AND REMOTELY CONTROLLED SWITCH MEANS IN AN ELECTRIC CIRCUIT CONTROLLING THE STOP MECHANISM OF THE LOOM, WHICH SWITCH MEANS ARE SYNCHRONOUSLY OPERATED WITH THE RECIPROCATING MOVEMENT OF THE SLAY, A WEFT STOP MOTION COMPRISING A STATIONARY SUPPORT SECURED TO THE LOOM FRAME AT THE REAR OF SAID REED, THIN FEELER MEANS CARRIED ON SAID SUPPORT FOR PIVOTAL MOVEMENT AND PASSAGE OF A FREE END THEREOF THROUGH A DENT OF THE REED, AN ELECTRIC CONTACT COMPRISING CONTACT MEANS AT THE OTHER END OF SAID FEELER MEANS AND MOVABLE THEREWITH AND STATIONARY CONTACT MEANS AT THE LOOM ELECTRICALLY CONNECTED TO SAID SWITCH MEANS, SAID ELECTRIC CONTACT REMAINING OPEN WHEN SAID FEELER MEANS ARE PIVOTED UPWARDLY BY A RESPECTIVE WEFT AND BEING CLOSED WHEN THE FREE END OF SAID FEELER MEANS IS IN DROPDOWN POSITION DUE TO LACK OF CONTACT WITH A WEFT, CLOSURE OF SAID ELECTRIC CONTACT AND SWITCH MEANS ACTUATING SAID STOP MECHANISM OF THE LOOM. 